This invention relates to an injection nozzle for liquid media. More particularly, it relates to an injection nozzle for injecting extremely small amounts of liquid fuel in combustion systems and engines.
An injector nozzle is known (see DE-PS 24 07 856) which has been found to be well suited for injecting fuel in amounts of from 0.05 to 10 kg/hour. This known nozzle includes a nozzle body having an inlet duct joined to swirl ducts feeding tangentially into a swirl space. In addition, a central return duct is disposed in the core of the body of the nozzle. The swirl space is substantially formed by a ring-shaped recess in the body of the nozzle and a cover plate having a central outlet opening is secured on the body. The cover plate and the frontal surface of the core, is limited or defined by the swirl space, and jointly form a disk-shaped gap. The gap connects the swirl space with the outlet opening of the cover plate on one side and with the return duct on the other side. The cross section of the outlet opening is several times the size of the superficies or outside facing surfaces of the disk-shaped gap.
However, the increasingly exacting requirements with respect to environmental protection and the fuel economy of combustion systems and engines requires a further reduction of the amounts of fuel injected. Still, the further refinement of injector nozzles has limitations. For example, any further reduction of the cross section of the bore would readily lead to clogging by impurities or contaminants or to occlusion caused by combustion. Attempts have been made to manufacture the body of the nozzle from gem or glass or the like, in order to minimize the boundary layer by using smooth surfaces, as the formation of a boundary layer presents another obstacle. Similarly, suction of the return bore would be unsuitable because this would cause undesirable noise.
Accordingly, it is an object of the invention to provide an improved injection nozzle of the above-specified type that can inject even extremely small amounts of fuel in a reliable manner without an appreciable additional expenditure.